package dkbta.util;

import java.io.IOException;
import java.io.Writer;

/**
 * A character stream that collects its output in a string builder, which can then be used
 * to construct a string.
 * <p>
 * Closing a <tt>StringBuilderWriter</tt> has no effect. The methods in this class can
 * be called after the stream has been closed without generating an <tt>IOException</tt>.
 */
public class StringBuilderWriter extends Writer{
	private final StringBuilder _builder;

	/**
	 * Create a new string writer using the default initial string-buffer size.
	 */
	public StringBuilderWriter(StringBuilder builder){
		this._builder = builder;
		lock = builder;
	}

	/**
	 * Write a single character.
	 */
	@Override
	public void write(int c){
		_builder.append((char)c);
	}

	/**
	 * Write a portion of an array of characters.
	 * 
	 * @param cbuf Array of characters
	 * @param off Offset from which to start writing characters
	 * @param len Number of characters to write
	 */
	@Override
	public void write(char cbuf[], int off, int len){
		if ((off < 0) || (off > cbuf.length) || (len < 0) || ((off + len) > cbuf.length)
				|| ((off + len) < 0)){
			throw new IndexOutOfBoundsException();
		}else if (len == 0){
			return;
		}
		_builder.append(cbuf, off, len);
	}

	/**
	 * Write a string.
	 */
	@Override
	public void write(String str){
		_builder.append(str);
	}

	/**
	 * Write a portion of a string.
	 * 
	 * @param str String to be written
	 * @param off Offset from which to start writing characters
	 * @param len Number of characters to write
	 */
	@Override
	public void write(String str, int off, int len){
		_builder.append(str.substring(off, off + len));
	}

	/**
	 * Appends the specified character sequence to this writer.
	 * <p>
	 * An invocation of this method of the form <tt>out.append(csq)</tt> behaves in
	 * exactly the same way as the invocation
	 * 
	 * <pre>
	 * out.write(csq.toString())
	 * </pre>
	 * 
	 * <p>
	 * Depending on the specification of <tt>toString</tt> for the character sequence
	 * <tt>csq</tt>, the entire sequence may not be appended. For instance, invoking
	 * the <tt>toString</tt> method of a character buffer will return a subsequence
	 * whose content depends upon the buffer's position and limit.
	 * 
	 * @param csq The character sequence to append. If <tt>csq</tt> is <tt>null</tt>,
	 *        then the four characters <tt>"null"</tt> are appended to this writer.
	 * @return This writer
	 */
	@Override
	public StringBuilderWriter append(CharSequence csq){
		if (csq == null)
			write("null");
		else
			write(csq.toString());
		return this;
	}

	/**
	 * Appends a subsequence of the specified character sequence to this writer.
	 * <p>
	 * An invocation of this method of the form <tt>out.append(csq, start,
	 * end)</tt>
	 * when <tt>csq</tt> is not <tt>null</tt>, behaves in exactly the same way as the
	 * invocation
	 * 
	 * <pre>
	 * out.write(csq.subSequence(start, end).toString())
	 * </pre>
	 * 
	 * @param csq The character sequence from which a subsequence will be appended. If
	 *        <tt>csq</tt> is <tt>null</tt>, then characters will be appended as if
	 *        <tt>csq</tt> contained the four characters <tt>"null"</tt>.
	 * @param start The index of the first character in the subsequence
	 * @param end The index of the character following the last character in the
	 *        subsequence
	 * @return This writer
	 * @throws IndexOutOfBoundsException If <tt>start</tt> or <tt>end</tt> are
	 *         negative, <tt>start</tt> is greater than <tt>end</tt>, or <tt>end</tt>
	 *         is greater than <tt>csq.length()</tt>
	 */
	@Override
	public StringBuilderWriter append(CharSequence csq, int start, int end){
		CharSequence cs = (csq == null ? "null" : csq);
		write(cs.subSequence(start, end).toString());
		return this;
	}

	/**
	 * Appends the specified character to this writer.
	 * <p>
	 * An invocation of this method of the form <tt>out.append(c)</tt> behaves in
	 * exactly the same way as the invocation
	 * 
	 * <pre>
	 * out.write(c)
	 * </pre>
	 * 
	 * @param c The 16-bit character to append
	 * @return This writer
	 */
	@Override
	public StringBuilderWriter append(char c){
		write(c);
		return this;
	}

	/**
	 * Return the buffer's current value as a string.
	 */
	@Override
	public String toString(){
		return _builder.toString();
	}

	/**
	 * Return the string builder itself.
	 * 
	 * @return StringBuilder holding the current buffer value.
	 */
	public StringBuilder getBuilder(){
		return _builder;
	}

	/**
	 * Flush the stream.
	 */
	@Override
	public void flush(){
	}

	/**
	 * Closing a <tt>StringBuilderWriter</tt> has no effect. The methods in this class
	 * can be called after the stream has been closed without generating an
	 * <tt>IOException</tt>.
	 */
	@Override
	public void close() throws IOException{
	}

}